How to Play DNA Builder
Click an empty DNA slot, then choose A, T, C or G using the on-screen buttons or keyboard. A pairs with T, and C pairs with G. On mutation levels, click a red incorrect base first to remove it, then repair the slot. Press R to restart the current sequence and P to pause.
About DNA Builder
DNA Builder is a free browser puzzle game where you repair incomplete DNA strands. Choose the correct nucleotide for every missing slot, follow the A-T and C-G pairing rules, remove mutations and build longer genetic sequences while protecting strand stability.